The annual Centre de Recherche en Cancérologie de Lyon (CRCL) symposium takes place from 25 to 27 September 2017. The 26 Septembre, a complet afternoon was dedicated to tumor heterogeneity and microenvironment. In this publication I would like to highlight some of the works presented this day.

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Cancer: The Evil Companion Corrupting Good Behaviour

ILARIA MALANCHI from Francis Crick Institute London UK – Tumor host interaction lab

Malanchi’s lab studies the strategies adopted by cancer cells to establish crucial interactions with their microenvironment (local tissue cells or inflammatory cells) during the process of tumor initiation as well as metastatic spreading. The final aim is to find approaches to interfere with the tumor-host crosstalk, a first step toward novel, more effective anti-cancer therapies. Ilaria Malanchi talk focused on the analysis and targeting of non-tumor-derived cells in the context of metastasis. The growth of a primary tumor will induce systemic changes helping metastatic spreading in distant organs. They identified neutrophils as the main component and driver of metastatic establishment within the pre–metastatic lung microenvironment. Most importantly they found that neutrophil-derived leukotrienes aid the colonization of distant tissue by selectively expanding the sub-pool of cancer cells that retain high tumorigenic potential. Genetic or pharmacologic inhibition of the leukotriene-generating enzyme Alox5 abrogates this leukotriene pro- metastatic activity and consequently reduces metastasis. Their results point the efficacy of targeted therapies against a specific microenvironment component, for example in this study, the neutrophil Alox5 enzyme.

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Antioxidant treatment can promote lung tumor formation during chronic oxidative stress

MARIELLE BREAU from Inserm U955, Créteil http://www.imrb.inserm.fr/equipes/s-adnot/

Oxidative stress is a major contributor to the lung alterations and chronic lung disease linked to cigarette smoke exposure. Antioxidants are viewed as molecule with a strong cancer protective ability but is strongly challenged since a few years. Indeed, it has been shown that N-acetylcysteine (NAC) increase the risk of lung cancer development in human and promote lung cancer progression in mice models with RAS or RAF activating oncogenic mutations. Antioxidants are also known to promote resistance/escape from senescence under various conditions. The objective of Marielle team work was to analyze lung alterations associated with chronic oxidative stress. they worked with the JunD-deficient mice model of chronic oxidative stress. JunD is also found decreased in human lung cancer. The loss of JunD is known to induce production of ROS and cell senescence. They performed chronic treatments of the mouse model with NAC (in drinking water at 40mg/kg) and studied the effects on tumor development at 4 month of age and at 12/18 month compared to vehicle treated mice. Same treatment was performed on WT mice. After 12 or more months of NAC treatment JunD deficient mice develop lung adenocarcinomas in 50% of mice vs 10% of the WT mice. JunD and WT mice didn’t develop lung carcinomas when treated with the vehicle. Even at 24 months. When compared 4 months vs 12-18 months mice, there is more oxidative stress and cell senescence in older mice lung (increase in p21, p16 expression and acid beta galactosidase activity). In JunD-KO mice these alterations were found higher than in WT mice. They found that NAC treatment lead to a decrease of the senescence biomarkers linking the escape from senescence to the development of adenocarcinomas. In conclusion, in their study, they show that NAC can promote lung tumor formations during aging. In a context of oxidative stress (JunD KO mice) tumorigenesis is dramatically induced. They show that the loss of JunD induce a strong chronic oxidative stress and promote cell senescence. The anti oxidant (NAC) treatment have a strong protective effect against senescence in JunD KO mice but may promote the development of lung carcinomas in a context of chronic oxidative stress.

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Non-canonical NOTCH3 signaling limits tumor angiogenesis

SHUHENG LIN – PhD student in Cancer Research Centre of Lyon-Université Claude Bernard Lyon 1

Nat Commun. 2017 Jul 18;8:16074.

Tumor angiogenesis is an attractive target for cancer therapy. However, clinical results targeting tumor angiogenesis are inconsistent. Most anti-angiogenic therapies target the vascular endothelial growth factors (VEGFs) signaling pathways. Notch signaling is a major regulator of these processes. Notch pathway activation follows the binding of the transmembrane ligands of the Delta/Serrate/LAG-2 (DSL) family, Delta-like and Jagged to Notch receptors. The ‘canonical pathway’ is a proteolytic cascade induced by ligand binding. These proteolytic cleavages release the intracellular domain of the Notch receptor (NICD), which translocate into the nucleus to mediate target genes activation. Whereas the role of Notch signaling is well described in developmental angiogenesis, its role in tumor angiogenesis is not clearly understood. Notch inhibition has been shown to induce endothelial cell death as well as vascular sprouting. Anti-ligand approaches produce an increase of endothelial cells sprouting. These paradoxical observations suggest that the role of Notch in tumor angiogenesis cannot be completely explained by canonical pathway. Notch3 expression is restricted to the vasculature in physiological condition. It is implicated in vascular disease (ex: mutations in CADASIL). The team asses the expression of Notch3 in human lung cancers. Notch3 was found strongly expressed in the vasculature of the tumor. In patients with histological normal peritumoral tissue, the expression of Notch3 was localized, in the vascular smooth muscle cells or in the mural cells of smaller vessels. In human malignant part, Notch3 is expressed in endothelial cells. In wild-type mice or in healthy part of lung from Kras+/G12D Notch3+/LacZ mice, expression of Notch3 (reported via LacZ mesurement) is restricted to mural cells and absent from normal vasculature endothelial cells. In adenocarcinomas LacZ is detected in tumoral cells and in healthy lung tissues. In mice peritumoral vasculature there is an endothelial cell restricted expression. In xenogrefous experiments of LLC1 lung cancer cells in Notch3+/LacZ mice, the same observation was done, with a Notch3 expression in tumoral associated endothelial cells. In vitro, they shown that coculture with epithelial cancer cells are sufficient to induce Notch3 expression in endothelial cells. They graft murine lung carcinoma LLC1 in wild-type and in Notch3LacZ/LacZ mice. In Notch3 silencing conditions, they obtain bigger tumors and enhance the expression of pro-angiogenic genes, suggesting that Notch3 limits tumor growth and vascularization in vivo. To understand how the absence of Notch3 would impact the tumor vascularization they work with HUVEC cell lines (low expression of Notch3). Forced expression of Notch3 induce endothelial cell death increasing sub-G1 cell population and leading to casp9 activation. Jag-1, a major Notch3 ligand is found upregulate in tumors, in cancer cells. He will promote endothelial survival and angiogenesis. It is poorly correlated in expression with Notch canonical pathway targets. In vitro they showed that Jag-1 expression rescues Notch3-induced endothelial cell death. Finally, they found that Notch3 was, in part, responsible for the anti-angiogenic effect of γ-secretase inhibitors (DAPT) described by other teams. DAPT treatment induced a reduced vascularization associated with a reduced tumor growth and could be reversed by deletion of Notch3. In conclusion, they proposed that targeting Jag-1 in tumor angiogenesis might therefore be an interesting approach. Targeting more specifically the Notch3-Jag-1 interaction could be advantageous allowing targeting of both the canonical Notch signaling in epithelial cells and Notch3-induced apoptosis in endothelial cells.

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The poster session was also full of very interesting works. Here is an example with these 2 works summaries

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Monocytic and granulocytic myeloid derived suppressor cells differentially regulate spatiotemporal tumour plasticity during metastatic cascade

Maria Ouzounova et al. Cancer Research Center of Lyon, Cancer Cell plasticity Department

In this work realized at the Georgia Cancer Center, Ouzounova et al demonstrated that monocytic (mMDSC) and granulocytes (gMDSC) subsets of myeloid- derived suppressor infiltrate the primary tumour and distant organs with different time kinetics and regulate spatiotemporal plasticity. Using co-culture experiment and trancriptome analyses in syngeneic mouse models, they provided that mMDSCs facilitate tumour dissemination by inducing EMT/CSC phenotype. In contrast, pulmonary gMDSC infiltrates support metastatic growth by reverting this phenotype and promoting cell proliferation. Furthermore, lung-derived gMDSCs isolated from tumour-bearing animals enhance metastatic growth of already disseminated tumour cells. Finally, MDSC- induced ‘metastatic signature’ derived from murine model predicts poor patient survival in the majority of human breast tumours analyzed suggesting that this MDSC infiltration may have a clinical implication in tumours. progression.

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Interactions via tunneling nanotubes and transfer of mirochondria between mesenchymal stem cells and target cancer cells. Effects on metabolism and biological function

Marie-Luce Vignais et al. INSERM U1183 “Cellules Souches, Plasticité Cellulaire, Médecine Régénératrice Et Immunothérapies”

Mesenchymal stem cells are recruited to the tumour microenvironment where they can affect cancer cells proliferation, metastasis and survival. MSCs can form connections via tunneling nanotubes (TNTs) and transfer mitochondria to the target cells. TNTs, are thin membrane channels that can allow distant intercellular connections. Vignais et al. designed the Mitoception protocol to transfer mitochondria isolated from MScs to target cells in order to measure their biological effect. They showed that the acquisition of MSC mitochondria enhances the OXPHOs activity of the recipient cells, both normal T cell or in MDA-MB-231 breast cancer cell line. They also showed that MSCs form TNTs and transfer mitochondria to glioblastoma stem cells isolated from resected tumors. It leads to increased resistance to temozolomide chemotherapy. They also are developing two chamber-microfluidic circuits to characterize the TNTs formation and the mitochondria trafficking between MSCs and glioblastoma cells.